The setting of bowling pins by means of ropes offers many advantages over other systems. However, in the past bowling alleys employing pin ropes were found to be less popular with the public. This was due to the fact that the rope did not permit the pins to fall as easily as they would fall if there were no ropes. As a result, scores on pin rope alleys were somewhat lower then on other bowling alleys. Most pin rope setting control devices as have been employed in the past, have employed a rope running over a pulley. At some time during the cycle of the apparatus the pulley was interengaged with some form of control. Either it was simply checked entirely, or alternatively it was engaged with some form of mechanical clutch system. In either case, the pulleys were never entirely free to run at the most critical time i.e. when the bowling pin was falling. At this time, it was always necessary in the past for the rope either to slide around the pulley, thereby creating a certain amount of friction, or it was necessary for the rope to turn the pulley against some degree of friction imposed by some mechanical linkage or clutch means. In some cases, the bowling pins would not fall in the correct pattern, thereby affecting the score of the bowler, and in other cases the pin might simply remain standing when, but for the drag on the rope, it would have fallen.
In addition to these disadvantages, the fact that there was friction either between the rope and the pulley, or between some parts of the pulley mechanism or clutch mechanism meant that every time the pins fell there was a certain degree of wear, and in fact this built up quite rapidly, and once the parts became worn the friction force increased and so the wear increased. As a result, these types of systems required quite a substantial amount of maintenance involving down time of the bowling alleys and costly delays while the parts were repaired.
In all such pin setting machines the pin ropes are tensioned by a common rope tensioning mechanism which operates all five pin ropes simultaneously, in the case of five pin bowling for example. A separate pin rope setting control device is provided for each rope, and it is required that the control device shall react to the falling of its respective pin so as to procure one cycle of operation of the common tensioning apparatus. The pin rope control device also incorporates a brake which then jams against the rope of the pin that has fallen and holds it up in an inoperative position, while permitting the remaining pins to be set once more. After all pins have fallen the tensioning device will then reset all five pins simultaneously. In order to perform satisfactorily it is essential that each of the five control devices for the five pin ropes shall react only when the pin has fallen, and not when it is merely brushed against so that it rocks but does not fall.
In order to achieve this degree of sensitivity in the prior art devices, some form of means for stopping the rope pulley at a predetermined point was provided.
A somewhat improved form of control device is shown in Canadian Pat. No. 844,454. In this device, the movement of the rope pulley is detected by means of a reed switch mounted along side the pulley, and a pair of magnets in the pulley activate the reed switch.
In order to preset the wheel, and its associated magnets, in a predetermined position each time the pin is reset, a wheel locking device is provided which automatically locks the wheel just prior to the pin descending in the resetting cycle. Thus, during resetting it is necessary for the pin to drag the rope around the pulley, until the pin reaches the floor. At this point, the wheel locking device is then deactivated leaving the the pulley free to rotate when the pin falls. This device, however, is unsatisfactory in that the repeated slippage of the rope over the pulley when it is held stationary during the resetting cycle eventually causes wear on the pulley, and these must then be replaced with consequent additional expense. Furthermore, this device requires the use of two electrical solenoids, one to operate the brake for the rope and the other to operate the stop device for the pulley thereby doubling the likelihood of breakdown, and consequent further delays and expense.